Quoting Thiemo Seufer <ths@networkno.de>:
> Arabic is "ar", IIRC. For groups of languages like cjk or indic it might
> make sense to split the packages further, or, if that's not feasible,
> use e.g. texlive-cjk-lang (but make sure the abbreviation is not ISO-style
> two-character).
ISO-style can be two-character (ISO 639-1) or three-letter (ISO 639-2).
The latter is IMHO more useful for TeX, as more languages have a code.
Arabic is either "ar" or "ara", Aramaic is "arc", Apache is "apa"...
"cjk" is currently not an ISO code, but it could be in the future.
However, cjk is well-known, so ISO would be very stupid to use this
code for anything else than zho-jpn-kor. Indic already has an ISO
language code: "inc".
Cheers, WB